The future of the de minimis concept

How low is low enough? Is "close to zero? Does detectability define importance? These and similar questions are addressed in this paper, which considers the concept of a "practical zero" or de minimis level of radiation and the future applications of that concept. After defining the concept and some widely used terms and summarizing the current status of the de minimis approach, this article surveys the activities of standards-setting and regulatory bodies throughout the world and their possible future approaches to applying the de minimis concept. Applications include conventional disposal of very-low-level wastes, ocean dumping, decontamination and decommissioning guidelines, and truncation of as low as reasonably achievable and collective dose calculations. Implications in areas beyond low-level radiation control are also addressed. These areas include nuclear accident risks and the risks associated with use of hazardous materials. The application of the de minimis concept to risks of all types is discussed, with a particular emphasis on the risks of carcinogenesis. The paper also presents a summary of methods for quantitatively setting actual levels that are deemed de minimis in specific cases. Finally, the problems inherent in a de minimis approach are discussed and an attempt is made to predict future developments.